Quantum internet based on atomic ensembles
Abstract
The recent technological goal to build larger networks for quantum communications, called quantum internet, relies not only on technical advances but on fundamental conceptual developments that took place throughout the last two to three decades. The main development being the recognition of the role quantum entanglement plays in quantum mechanics and, consequently, on our overall descriptionof the natural phenomena around us. The global description of systems purely by quantum mechanics has strong fundamental implications as all processes are coherent and no information is lost. Most of the surprising developments in quantum networks come from this radically coherent perspective, which has been systematically confirmed by the experiments. This global quantum perspective, however, is intrinsically multipartite and complex, requiring the development of new concepts and approaches. The idea of quantum internet takes a central stage in this effort as it provides economic/strategic motivation and more concrete goals to a rather abstract and overly broad scientific problem. This project#s goal is to advance the field of quantum networks by implementing two key ideas: a newclass of multipartite quantum entanglement from an ensemble of two-level atoms, and an atomic memory for ultrabroadband single photons. For the multipartite entanglement, in these first three years we plan to measure first the quadripartite entanglement in light scattered by cold two-level atoms due to excitation by two counter-propagating laser beams. This will require the characterization of bipartite entanglements for the different pairs of modes of the quadripartite state. Such achievement would extend the observationof multipartite entanglement to the simplest and most widely applied system to model light-matter interaction. Important developments could occur in different directions, like observing different types of multipartite entanglement depending on the excitation fields, implementing atomic memories with the atomic external degrees of freedom, and exploring higher order nonlinearities. For the memory of the ultrabroadband photon, we plan to first measure the high absorption of a weak pulse of about 100fs duration in a two-photon sequential transition. For that, we are going to use a high-power amplified control pulse, a spatial light modulator for coherentcontrol, and a heated vapor cell to tune the atomic density. Once we succeed in significantly absorbing this weak pulse, we are going to substitute it by a single photon from a spontaneous parametric-down-conversion source and characterize the collective atomic state generated after it is absorbed by the atomic ensemble. The success here would finally combine atomic memories with the whole field of quantum correlations in spontaneous parametric down-conversion, a workhorse for quantum optics and quantum information. This would have far reaching consequences for quantum information, as, for example, providing a way to connect satellite-based quantum communications with local quantum networks. In practice, the first steps along this line has the potential to create already a new field, with the transduction of quantum information from femtosecond to microseconds timescales and the need to control new types of collective atomic states.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 12, 2023
- Source ID
- N629092312014
Entities
People
- Daniel Barbosa
Organizations
- Office of Naval Research
- United States Navy